Model spalling of cover concrete

[capitanhook]

Hi everybody and congratulations for this great forum.

I'm using seismostruct 7 for some academical studies and i'm conducting pushover analysis on RC columns.

I'm using mander model for concrete but i see that the unconfined stress-strain curve does not drop to zero at a strain equals to the spalling strain.
I verified this by inserting two stress points: one in the most compressed fiber of core concrete, one in the most compressed fiber of cover concrete.

Can i somewhat model this behaviour correctly?
Do i need to use a previous version of seismostruct to solve this?

Thank you for your help,
Rob

[z.gronti]

Dear capitanhook,

Due to its Constitutive law, the Mander et al. nonlinear concrete model keeps a residual strength.

[capitanhook]

Dear Zoi,
thank you for the reply.

Does the criterion for the strength apply to a single fiber or to the entire element?
I already tried to use this method and i think it reduces the strength of the whole section, and this clearly led to unacceptable analysis results.

[z.gronti]

Dear capitanhook,

The performance criteria apply to all the fibres of the element.

[capitanhook]

So it is impossible in seismostruct to model the real phenomenon of spalling such that the RC section progressively loses strength (and stiffness),

isn't it?

Thank you again

[seismosoft]

Hi capitanhook,

The progressive loss of strength and stiffness of the section is effectively modeled by the constitutive stress-strain curve of the concrete material. All the SeismoStruct models for concrete feature a peak capacity, after which the strength reaches the residual strength.For more details see the Materials module and the relevant sections in help system and the users manual.

Seismosoft Support